Internal combustion engine and its operating mode

ABSTRACT

Internal combustion engine and method of operating the engine, wherein the engine includes at least one cylinder and a cylinder head. At least one piston is included having a top dead center position wherein the piston is disposed near the cylinder head and a bottom dead center position wherein the piston is disposed away from the cylinder head. The piston and cylinder are movable with respect to one another. A crankshaft is provided. At least one intake valve and at least one exhaust valve are included. Each valve is controlled to respectively allow gas intake and exhaust gas discharge. A movable recuperator is disposed between the cylinder head and the piston. The recuperator allows at least one of intake gas to flow from the intake valve and through the recuperator, and exhaust gas to flow through the recuperator and to the exhaust valve. The recuperator moves only when the piston is in a region of the top dead center position and in a region of the bottom dead center position. The method includes introducing a compressed gaseous medium into the cylinder via the intake valve when the piston is in the region of the top dead center position, closing the intake valve, heating the compressed gaseous medium using the recuperator, combusting the gaseous medium so as to move the piston to the bottom dead center position, and opening the exhaust valve to discharge the combusted gaseous medium from the cylinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage Application of InternationalApplication No. PCT/AT98/00199, filed Aug.25, 1998. Further, the presentapplication claims priority under 35 U.S.C. § 119 of Austrian PatentApplication No. A-1416/97 filed on Aug. 25, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the operating mode of an internal combustionengine having at least one piston and cylinder that can be moved withrespect to one another and interact, in which a crankshaft can be drivenpreferably by a piston by way of a power transmission and in which thepiston in the cylinder occupies in succession a bottom and a top deadcenter position, forming a largest and a smallest inner cylinderchamber, and the cylinder chamber can be sealed periodically, forexample, by controlled valves.

The invention further includes an internal combustion engine having atleast one piston and cylinder that can be moved with respect to oneanother and interact, in which a crankshaft can be driven preferably bya piston by way of a power transmission and in which the piston in thecylinder occupies in succession a bottom and a top dead center position,forming a largest and a smallest inner cylinder chamber, and the innercylinder chamber can be sealed periodically, for example, by controlledvalves, against a gas feed- and an exhaust gas discharge device, andoptionally has a mechanism for the introduction and/or ignition of anoperating fluid or fuel mixture.

2. Description of Background and Revelant Information

The operating mode of known combustion engines having a piston moved ina cylinder essentially includes a loading stroke with the introductionof air or a combustible gas mixture in the inner cylinder chamber, aswell as a compression thereof by the piston moved into its top deadcenter position, after which, in a power stroke, a combustion ofoperating fluid takes place under elevation of temperature and pressure,and resulting in displacement of the piston into its bottom dead centerposition, whereupon, in an emission stroke, the burned gases or exhaustgases are discharged from the inner cylinder chamber. The sequence ofgas feed, compression, and exhaust gas discharge is controlled bymovable sealing devices, in particular valves, in the region of thecylinder head, as a function of the rotation of the crankshaft. Theperformance of this process, which is generally called the four-cycleprinciple, can be brought to higher specific levels by pressing air orcombustible gas mixture into the inner cylinder chamber, for example, byway of a turbo-supercharger or compressor, because the filing of thecylinder with combustible medium can thus be increased, in particular ahigh engine speeds.

In the two-cycle principle, access to a feed and exhaust gas channel inthe cylinder wall is opened by the piston itself in the region of thebottom dead center position, so that gas can be transported through theinner cylinder chamber, and exhaust gas can be “flushed” with a chargeof fresh gas. After the charge of fresh gas or gas mixture, which iseffected by elevating its pressure, the piston is moved to the top deadcenter position with compression of the fresh gas, in which region acombustion of the operating fluid is initiated. The pressure of thefresh gas or gas mixture is elevated by a displacement effect of thepiston itself and/or by a means for elevating pressure.

All known operating modes of internal combustion engines, however, havein common the disadvantages that, on the one hand, no adiabatic orisentropic expansion of the combustion gas to essentially the ambientpressure is allowed or can be allowed to occur and, on the other hand,an isochoric dissipation of the inherent heat in the combustion gastakes place as it is discharged from the inner cylinder chamber and thusthe utilization of the energy of the operating fluid or combustion gasis low.

SUMMARY OF THE INVENTION

According to the invention, there is provided an internal combustionengine comprising at least one cylinder. A cylinder head is provided. Atleast one piston is included having a top dead center position whereinthe piston is disposed near the cylinder head and a bottom dead centerposition wherein the piston is disposed away from the cylinder head. Thepiston and cylinder are movable with respect to one another. Acrankshaft is included. At least one intake valve and at least oneexhaust valve are provided. Each valve is controlled to respectivelyallow gas intake and exhaust gas discharge. A movable recuperator isdisposed between the cylinder head and the piston. The recuperatorallows at least one of intake gas to flow from the intake valve andthrough the recuperator and exhaust gas to flow through the recuperatorand to the exhaust valve. The recuperator moves only when the piston isin a region of the top dead center position and in a region of thebottom dead center position.

The recuperator may be movable away from the piston when the piston isin the region of the top dead center position and may be movable towardsthe piston when the piston is in the region of the bottom dead centerposition. The recuperator may be movable between at least a firstposition in which a space is defined between the cylinder head and atleast a second position in which the space is reduced, and a combustionchamber may be defined between the piston and at least the recuperator.The recuperator may comprise a cross section which is essentially thesame as a cross section of the cylinder. The recuperator may be disposedbetween the valves and the piston, and the recuperator may comprise amechanism for moving the recuperator. The recuperator may comprise atleast one of a metal, a ceramic, and a catalytically effective coating.The engine may further comprise a pressure elevating device adapted tofeed a gaseous medium to the internal combustion engine. The pressureelevating device may be driven by one of the crankshaft and an externaldrive. The engine may further comprise a control device coupled to anintake side of the intake valve, a pressure accumulator coupled to thecontrol device, and a pressure elevating device coupled to the controldevice, wherein the pressure elevating device is adapted to feed agaseous medium to the internal combustion engine. At least a portion ofthe cylinder may be at least one of externally non-cooled andheat-insulated.

The invention also provides for a method of operating an internalcombustion engine which includes at least one cylinder, a cylinder head,at least one piston having a top dead center position defined by thepiston being disposed near the cylinder head and a bottom dead centerposition defined by the piston being disposed away from the cylinderhead, the piston and cylinder being movable with respect to one another,a crankshaft, at least one intake valve and at least one exhaust valve,each valve being controlled to respectively allow gas intake and exhaustgas discharge, and a movable recuperator disposed between the cylinderhead and the piston, the recuperator allowing at least one of intake gasto flow from the intake valve and through the recuperator, and exhaustgas to flow through the recuperator and to the exhaust valve, the methodcomprising introducing a compressed gaseous medium into the cylinder viathe intake valve when the piston is in the region of the top dead centerposition, closing the intake valve, heating the compressing the gaseousmedium using the recuperator, combusting the gaseous medium so as tomove the piston to the bottom dead center position, opening the exhaustvalve to discharge the combusted gaseous medium from the cylinder,wherein recuperator moves only when the piston is in a region of the topdead center position and in a region of the bottom dead center position.

The method may further comprise moving the recuperator away from thepiston when the piston is in the region of the top dead position, andmoving the recuperator towards the piston when the piston is in theregion of the bottom dead center position. The method may furthercomprise moving the recuperator between at least a first position inwhich a space is defined between the cylinder head and at least a secondposition in which the space is reduced, wherein a combustion chamber isdefined between the piston and at least the recuperator. The recuperatormay comprises a cross section which is essentially the same as a crosssection of the cylinder. The method may further comprise moving therecuperator via a mechanism for moving the recuperator, wherein therecuperator is disposed between the valves and the piston. Therecuperator may comprise at least one of a metal, a ceramic, and acatalytically effective coating. The method may further comprise feedingthe compressed gaseous medium to the internal combustion engine via apressure elevating device. The method may further comprise driving thepressure elevating device via one of the crankshaft and an externaldrive. The method may further comprise coupling a control device to anintake side of the intake valve, coupling a pressure accumulator to thecontrol device, and coupling a pressure elevating device to the controldevice, wherein the pressure elevating device is adapted to feed thecompressed gaseous medium to the internal combustion engine. The methodmay further comprise at least one of externally non-cooling andheat-insulating at least a portion of the cylinder.

According to another aspect of the invention, there is provided aninternal combustion engine comprising at least one cylinder. A cylinderhead is disposed at one end of the cylinder. A crankshaft is included.At least one piston is coupled to the crankshaft. The piston is movablewithin the cylinder between at least a top dead center position and atleast a bottom dead center position. At least one intake valve and atleast one exhaust valve is included. Each valve is controlled torespectively allow gas intake and gas discharge. A movable recuperatoris disposed between the cylinder head and the piston. The recuperatorallows each of intake gas to flow from the intake valve and through therecuperator and exhaust gas to flow through the recuperator and outthrough the exhaust valve, wherein the recuperator is movable away fromthe piston when the piston is in a region of the top dead centerposition and wherein the recuperator is movable towards the piston whenthe piston is in a region of the bottom dead center position.

The invention further provides an internal combustion engine comprisingat least one cylinder. A cylinder head is included. At least one pistonhas a top dead center position wherein the piston is disposed near thecylinder head and a bottom dead center position wherein the piston isdisposed away from the cylinder head. The piston and cylinder aremovable with respect to one another. A crankshaft is included. At leastone intake valve and at least one exhaust valve is included. Each valveis controlled to respectively allow gas intake and exhaust gasdischarge. A movable recuperator is disposed between the cylinder headand the piston. The recuperator allows at least one of intake gas toflow from the intake valve and through the recuperator and exhaust gasto flow through the recuperator and to the exhaust valve. A controldevice is coupled to an intake side of the intake valve. A pressureaccumulator is coupled to the control device. A pressure elevatingdevice is coupled to the control device. An external drive is providedfor driving the pressure elevating device. The pressure elevating deviceis adapted to feed a gaseous medium to the internal combustion engine.

The invention is intended to set up an operating mode of an internalcombustion engine by which the energy utilization of the operating fluidduring the combustion is to be considerably increased. The inventionprovides for an internal combustion engine with which a considerablyimproved degree of efficiency is achieved.

The invention thus provides for a generic operating mode in that in aloading process in the inner cylinder chamber formed in the region ofthe top dead center position of the piston, a compressed gaseous mediumis introduced with the opening of at least one intake sealing mechanism,the inner cylinder chamber is closed, and the compressed gaseous mediumis heated by recuperation, whereupon a power stroke combustion isallowed to occur under elevated temperature and pressure in the gaseousmedium confined in the cylinder chamber and brought to elevatedtemperature. The piston is pressed to its bottom dead center positionunder reduction of the temperature and pressure of the burned medium,after which in an emission stroke at least one exhaust sealing mechanismis opened. The combustion- or exhaust gas is discharged from the innercylinder chamber by way of the piston moved to its top dead centerposition, under recuperative withdrawal of thermal energy.

The advantages achieved with the invention consist in particular inthat, on the one hand, it is made possible for the combustion gas toexpand to approximately the ambient pressure, resulting in an improvedenergy utilization. On the other hand, the heat or energy remaining inthe combustion gas is further reduced according to the invention by heatdissipation into a recuperator, so that the exhaust gas can be broughtto a considerably lower energy level and thus the energy balance of theprocess is considerably improved by introducing energy stored in therecuperator into the fresh gas. The result is that the residual energyin the finally discharged exhaust gas, which is not usable for theprocess, is considerably reduced and that the operating mode has aconsiderably higher degree of efficiency as far as the energy used orintroduced by means of the operating fluid or gas mixture is concerned.

Here, it is particularly advantageous if, during the power stroke,provision is made for the pressure to be reduced to essentially theambient pressure when the bottom dead center position of the piston isreached.

When diesel, gasoline, or similar fuels are used, it can be consideredfavorable if, during the loading process, an oxygen-containing gaseousmedium or an oxygencontaining gas, in particular combustion air, ispressed into the cylinder chamber and is heated by recuperation therebyor therein, whereupon, in the power stroke, operating fluid or fuel isintroduced into the cylinder chamber and is preferably brought tocombustion by self-ignition or optionally by.externally suppliedignition. The required conditions for combustion of the introducedoperating fluid and utilization of its energy can be optimized byadjusting the intake pressure for the gas and the amount of the fluid.

If, as can be further provided for in a favorable manner, in the loadingprocess, a combustible gaseous medium, in particular a gasoline or thelike and/or gas/air mixture, is pressed into the cylinder chamber andheated therein, whereupon, during the power stroke, this combustion gasis brought to combustion by externally supplied ignition orself-ignition, it is possible according to the invention to use fuels,for example, for gasoline, diesel, or gas motors with considerablyimproved degrees of efficiency.

In the operating mode according to the invention, however, as far as thedischarge is concerned, it is also particularly important with respectto an improvement in the degree of efficiency for the gaseous mediumprovided for the loading process to be isothermally condensed orcompressed, introduced into the inner cylinder chamber, and heatedisochorically therein, after which, during the power stroke, a furtherisochoric, optionally isochoric and/or isobaric, temperature elevationtakes place owing to the combustion, with a subsequent isentropicexpansion of the combustion gas effected by the movement of the pistonand, when the combustion gas is discharged from the inner cylinderchamber during the exhaust stroke, the perceptible heat is at leastpartially removed isobarically from the exhaust gas. Only when thisstroke sequence or sequence of steps is maintained can a desirably highthermal degree of efficiency be achieved during the combustion of theoperating fluid or gas.

Here, it is particularly important for the gaseous medium to be heatedrecuperatively before the power stroke by way of the thermal energy,which is stored in a storage mechanism and essentially distributeduniformly across the cross section as the combustion gases aredischarged.

Here, it is particularly advantageous for the recuperative heating ofthe gaseous medium to be carried out in the inner cylinder chamber.

An internal combustion engine of the initially named type is definedaccording to the invention in that it has a recuperator through whichthe fed gas and the combustion gas or exhaust gas can flow alternately.

According to the invention, the residual heat of the exhaust gas isfurther reduced by way of the recuperator, and this energy can berecycled to the operating process, which leads to a considerableincrease in the degree of thermal efficiency of the internal combustionengine.

Here, it is particularly favorable for the recuperator to be arranged inthe inner cylinder chamber such that it essentially fills the crosssection of the cylinder.

A further advantage with respect to an optimum functioning of the novelinternal combustion engine is achieved if the recuperator is arranged sothat it can be moved in the cylinder chamber, in particular so that itcan be displaced in the direction of the cylinder axis. Thus, anadvantageously high percentage of unburned gasoline and the like orgas/air mixture or the combustion air can be brought to a desirably hightemperature or the recuperative heat exchange can be optimized.

Here, it can be advantageous for the movable recuperator mounting and/ora recuperator part to be additionally designed as an intake and/orexhaust sealing mechanism(s).

In order to achieve both high efficiency and high durability, it can befavorable for the recuperator to be formed of metal and/or ceramic.

It is particularly preferred if the recuperator carries a catalyticcoating. Thus, on the one hand, as is known per se, the percentage ofcarbon monoxide in the exhaust gas is reduced, but, on the other hand,the thermal energy formed during the catalysis is utilizable for heatingthe gaseous medium introduced into the inner cylinder chamber and thedegree of thermal efficiency of the internal combustion engine isimproved.

In order to control directly the loading of the internal combustionengine, and also with respect to its most functionally favorable design,it can be advantageous for a pressure elevating device to be arranged inthe feed area of the gaseous medium. Here, it is particularlyadvantageous for an evenly distributed load operation, if the pressureelevating device can be driven by the working piston by way of acoupling to the crankshaft or to the working piston. As far as theoverall degree of efficiency is concerned, however, it can also befavorable if the pressure elevating device can be driven at leastpartially by externally supplied energy. It is also possible, forexample, in a vehicle, to obtain the externally supplied energy from thebraking process.

It is particularly advantageous if a pressure accumulator for thegaseous medium, which can be utilized preferably by way of a controldevice, is arranged in the region of the pressure elevating device orbetween it and the intake sealing mechanism in the gas feed device, andif this pressure accumulator can be charged by the pressure elevatingdevice by way of an external drive via mechanical coupling mechanism tothe pressure elevating device, optionally independently of the operationof the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below based on drawingsshowing merely one embodiment:

FIG. 1 shows schematically the construction of a device according to theinvention;

FIGS. 2 through 7 show the sequence of the process of the invention inits essential steps.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, a cylinder 1 is shown in which a piston 2 can be moved, withthe piston 2 being coupled with a crankshaft 8. Combustion air V or acombustible gas mixture can be fed to a pressure elevating device 5, bywhich this medium is prepared for a control device 6, preferably havingan attached pressure accumulator 7. By utilizing this pressure elevatingdevice 5, which is designed so that it can be connected with thecrankshaft 8 or an external drive 9 by way of a coupling 81, 91respectively, and/or with the pressure accumulator 7, a gaseous medium Mis prepared in a gas feed device 11 for the cylinder 1 via the controldevice 6. A recuperator 3 is arranged in the cylinder 1 in the region ofthe cylinder head such that it essentially fills the cross section ofthe cylinder 1. Combustion or exhaust gas A can be removed from theinner cylinder chamber by way of an exhaust gas discharge device 13.

In FIG. 2, a loading process of an internal combustion engine of theinvention is shown schematically, in which an isothermally condensedgaseous medium M is introduced into the inner chamber of a cylinder Ithrough a gas feed device 11 when an intake sealing mechanism 12 isopened. A recuperator 3 with elevated temperature is then situated inthe vicinity of a piston 2, which is situated in the region of its topdead center position, opening an upper inner cylinder chamber.

After the intake sealing mechanism 12 has been closed as shown in FIG.3, the recuperator 3 is moved into the upper inner cylinder chamber byway of a displacing device 31, whereupon the gaseous medium flowsthrough the recuperator 3 and is thereby heated isochorically.

In FIG. 4, the situation during combustion of an operating fluid or fuelmixture is illustrated in which the combustion presses the piston 2 inthe direction of the arrow into a bottom dead center position startingfrom an ignition or introduction mechanism in the region E of thecylinder 1.

When the bottom dead center position U of the piston 2 is reached, asshown in FIG. 5, the combustion gas can essentially have assumed theambient pressure after an isentropic expansion of the combustion gas.

In the further sequence of the operating mode of the invention, as shownin FIG. 6, the recuperator 3 is displaced in the direction of the bottomdead center position U, and an exhaust sealing mechanism 14 is openedand a connection to an exhaust gas discharge device 13 is created. Bysubsequent movement of the piston 2 in the direction of the arrowtowards its top dead center position, exhaust gas A is conveyed throughthe recuperator 3, with the recuperator 3 being heated as the exhaustgas A cools. In the top dead center position of the piston 2 in thecylinder 1, as shown in FIG. 7, the exhaust sealing mechanism 14 iscaused to close, after which the internal combustion engine is madeready for a further loading process.

Because the exhaust gas A is cooled by way of a recuperator 3 beforebeing discharged into an exhaust gas device 13, thermal stressing of thecylinder head and exhaust sealing mechanism 14 is reduced. It is evenpossible to provide an insulation of at least parts of the cylinder 1 toimprove the degree of efficiency of the internal combustion engine.

What is claimed is:
 1. An internal combustion engine comprising: atleast one cylinder; a cylinder head; at least one piston having a topdead center position wherein the piston is disposed near the cylinderhead and a bottom dead center position wherein the piston is disposedaway from the cylinder head; the piston and cylinder being movable withrespect to one another; a crankshaft; at least one intake valve and atleast one exhaust valve, each valve being controlled to respectivelyallow gas intake and exhaust gas discharge; and a movable recuperatordisposed between the cylinder head and the piston, the recuperatorallowing at least one of: intake gas to flow from the intake valve andthrough the recuperator, and exhaust gas to flow through the recuperatorand to the exhaust valve, wherein the recuperator moves only when thepiston is in a region of the top dead center position and in a region ofthe bottom dead center position.
 2. The engine of claim 1, wherein therecuperator is movable away from the piston when the piston is in theregion of the top dead center position and wherein the recuperator ismovable towards the piston when the piston is in the region of thebottom dead center position.
 3. The engine of claim 1, wherein therecuperator is movable between at least a first position in which aspace is defined between the cylinder head and at least a secondposition in which the space is reduced, and wherein a combustion chamberis defined between the piston and at least the recuperator.
 4. Theengine of claim 1, wherein the recuperator comprises a cross sectionwhich is essentially the same as a cross section of the cylinder.
 5. Theengine of claim 1, wherein the recuperator is disposed between thevalves and the piston, and wherein the recuperator comprises a mechanismfor moving the recuperator.
 6. The engine of claim 1, wherein therecuperator comprises at least one of a metal, a ceramic, and acatalytically effective coating.
 7. The engine of claim 1, furthercomprising a pressure elevating device adapted to feed a gaseous mediumto the internal combustion engine.
 8. The engine of claim 7, wherein thepressure elevating device is driven by one of the crankshaft and anexternal drive.
 9. The engine of claim 1, further comprising: a controldevice coupled to an intake side of the intake valve; a pressureaccumulator coupled to the control device; and a pressure elevatingdevice coupled to the control device, wherein the pressure elevatingdevice is adapted to feed a gaseous medium to the internal combustionengine.
 10. The engine of claim 1, wherein at least a portion of thecylinder is at least one of externally non-cooled and heat-insulated.11. A method of operating an internal combustion engine which includesat least one cylinder, a cylinder head, at least one piston having a topdead center position defined by the piston being disposed near thecylinder head and a bottom dead center position defined by the pistonbeing disposed away from the cylinder head, the piston and cylinderbeing movable with respect to one another, a crankshaft, at least oneintake valve and at least one exhaust valve, each valve being controlledto respectively allow gas intake and exhaust gas discharge, and amovable recuperator disposed between the cylinder head and the piston,the recuperator allowing at least one of intake gas to flow from theintake valve and through the recuperator, and exhaust gas to flowthrough the recuperator and to the exhaust valve, the method comprising:introducing a compressed gaseous medium into the cylinder via the intakevalve when the piston is in the region of the top dead center position;closing the intake valve; heating the compressed gaseous medium usingthe recuperator; combusting the gaseous medium so as to move the pistonto the bottom dead center position; and opening the exhaust valve todischarge the combusted gaseous medium from the cylinder, whereinrecuperator moves only when the piston is in a region of the top deadcenter position and in a region of the bottom dead center position. 12.The method of claim 11, further comprising: moving the recuperator awayfrom the piston when the piston is in the region of the top deadposition; and moving the recuperator towards the piston when the pistonis in the region of the bottom dead center position.
 13. The method ofclaim 11, further comprising: moving the recuperator between at least afirst position in which a space is defined between the cylinder head andat least a second position in which the space is reduced, wherein acombustion chamber is defined between the piston and at least therecuperator.
 14. The method of claim 11, wherein the recuperatorcomprises a cross section which is essentially the same as a crosssection of the cylinder.
 15. The method of claim 11, further comprising:moving the recuperator via a mechanism for moving the recuperator,wherein the recuperator is disposed between the valves and the piston.16. The method of claim 11, wherein the recuperator comprises at leastone of a metal, a ceramic, and a catalytically effective coating. 17.The method of claim 11, further comprising: feeding the compressedgaseous medium to the internal combustion engine via a pressureelevating device.
 18. The method of claim 17, further comprising:driving the pressure elevating device via one of the crankshaft and anexternal drive.
 19. The method of claim 11, further comprising: couplinga control device to an intake side of the intake valve; coupling apressure accumulator to the control device; and coupling a pressureelevating device to the control device, wherein the pressure elevatingdevice is adapted to feed the compressed gaseous medium to the internalcombustion engine.
 20. The method of claim 11, further comprising: atleast one of externally non-cooling and heat-insulating at least aportion of the cylinder.
 21. An internal combustion engine comprising:at least one cylinder; a cylinder head disposed at one end of thecylinder; a crankshaft; at least one piston coupled to the crankshaft;the piston being movable within the cylinder between at least a top deadcenter position and at least a bottom dead center position; at least oneintake valve and at least one exhaust valve, each valve being controlledto respectively allow gas intake and gas discharge; and a movablerecuperator disposed between the cylinder head and the piston, therecuperator allowing each of intake gas to flow from the intake valveand through the recuperator and exhaust gas to flow through therecuperator and out through the exhaust valve, wherein the recuperatoris movable away from the piston when the piston is in a region of thetop dead center position and wherein the recuperator is movable towardsthe piston when the piston is in a region of the bottom dead centerposition.
 22. An internal combustion engine comprising: at least onecylinder; a cylinder head; at least one piston having a top dead centerposition wherein the piston is disposed near the cylinder head and abottom dead center position wherein the piston is disposed away from thecylinder head; the piston and cylinder being movable with respect to oneanother; a crankshaft; at least one intake valve and at least oneexhaust valve, each valve being controlled to respectively allow gasintake and exhaust gas discharge; and a movable recuperator disposedbetween the cylinder head and the piston, the recuperator allowing atleast one of: intake gas to flow from the intake valve and through therecuperator, and exhaust gas to flow through the recuperator and to theexhaust valve, a control device coupled to an intake side of the intakevalve; a pressure accumulator coupled to the control device; a pressureelevating device coupled to the control device; and an external drivefor driving the pressure elevating device, wherein the pressureelevating device is adapted to feed a gaseous medium to the internalcombustion engine.